Knee osteoarthritis (OA) is a chronic, progressive degenerative disease with accompanying joint pain, stiffness, and deformity.1 Knee OA is a common joint disease, with an incidence of 30% of the population older than 60 years.2 The initiation and progression of knee OA involves mechanical, structural, genetic, and environmental factors.3 Knee varus deformities, characterized by a mechanical femorotibial axis of less than 180° on full-leg standing anteroposterior (AP) radiographs and narrowed medial joint space, are common in patients with knee OA and affect 74% of patients with idiopathic OA.4 Although it has been reported that even in healthy knees the medial compartment bears 60% to 80% of the load,5 no one has precisely documented what contributes to this uneven load distribution. The current belief is that the load is distributed along the mechanical axis, which is generally medial to the center of the knee.
High tibial osteotomy and total knee arthroplasty are the 2 methods used for treating knee OA. High tibial osteotomy can be a technically demanding procedure and may result in complications, including neurovascular injury, iatrogenic fracture, and nonunion.6,7 Total knee arthroplasty can correct lower extremity alignment, relieve pain, and improve function significantly. However, for younger, active patients or patients with moderate OA, it may not be the treatment of choice.8
Based on previous image and clinical studies, the authors believe that the lateral support provided to the osteoporotic tibia by the fibula–soft tissue complex may lead to the nonuniform settlement and degeneration of the plateau bilaterally.9,10 This may result in the load from the normal distribution shifting farther medially to the medial plateau and consequently lead to knee varus, aggravating the progression of medial compartment OA of the knee joint. Using this logic, the authors have performed a proximal fibular osteotomy to relieve the increased loading force on the medial compartment for treatment of medial compartment OA of the knee joint. The goal of this retrospective study was to evaluate the radiographic and clinical outcomes of patients with medial compartment OA treated by partial fibular osteotomy with a mean follow-up of 49.1 months.
Materials and Methods
Institutional review board approval was obtained for this study (No. Ke2014-004-1). All patients agreed to participate in this study and gave informed consent.
Inclusion criteria included patients with moderate to severe symptomatic medial compartment OA of the knee, who had an indication for a surgical procedure, and who were able to give informed consent for the surgery (Figure 1). Exclusion criteria included patients with posttraumatic knee OA or inflammatory joint disease and patients with a history of previous operations or fractures. Patients in whom conservative management has failed and who have radiographic evidence of significant varus are good candidates for partial fibular osteotomy.11 Between January 1996 and April 2012, a total of 156 patients with medial compartment OA were candidates to receive fibular osteotomy. Forty-six patients were excluded for the following reasons: lost to follow-up (n=21), fear of adverse effects from the procedure (n=10), and nonprocedure-related reasons (n=15).
Preoperative anteroposterior (A) and lateral (B) radiographs of a 64-year-old woman showing a severe degree of medial compartment osteoarthritis and knee varus deformity.
The primary outcome measure was the difference in femorotibial angle pre- vs postoperatively, with a minimum 2-year follow-up. The degree of correction was an important factor in patient outcome and gave an objective measurement. The method of measurement was that of Wang et al12 (Figure 2), in which the angle a stood for the femorotibial angle (FTA) and the line EF stood for the lateral joint space of the knee joint.
Diagrams of the femorotibial angle and lateral knee joint space measurement. Line OA is the femoral shaft anatomical axis; line OB is the tibial shaft anatomical axis; and angle a is the femorotibial angle (A). Line CD runs through the tops of the medial and lateral condyles of the tibia; point E is the outer one-sixth point of line CE; and line EF is perpendicular to line CD and stands for the distance of the lateral knee joint space (B).
The secondary outcome measure was pain measured by the visual analog scale (VAS).13 Data regarding age, sex, laterality, severity of OA, radiographic FTA and lateral joint space, and preoperative American Knee Society Score (KSS)14 were recorded for all patients at baseline and at each follow-up visit.
Under epidural anesthesia, the patients were placed in the supine position with the lower limb tourniquet inflated. First, the fibular head was marked. To avoid injury to the common fibular nerve and tibial attachments of the soft tissue structures crossing the knee joint, a lateral incision of 3 to 5 cm was made at the proximal third of the fibula. The fascia was then incised in line with the septum between the peroneus and soleus, the muscles were separated, and the fibula was exposed. A 2-cm section of the fibula was removed 6 to 10 cm below the fibular head with the use of an oscillating saw or fret saw. Following resection, the fibula ends were sealed with bone wax. The muscles, fascia, and skin were sutured separately after the incision had been irrigated with a large volume of normal saline. Postoperatively, the patients were ambulated as soon as pain could be tolerated.
Patients were followed up by 3 of the authors (C.-X.L., B.-C.C., Y.-Z.Z.) at 1, 3, 6, and 12 months postoperatively and then annually thereafter. Weight-bearing AP and lateral radiographs of the affected knee were taken at each follow-up (Figure 3).
Anteroposterior (A) and lateral (B) radiographs obtained immediately postoperatively showing the recovered medial joint space and a fibular defect.
Statistical analyses were performed using SPSS version 19.0 statistical software for Windows (IBM, Armonk, New York). Continuous variables were expressed as mean±SD and dichotomous variables were expressed as percentages. Two-tailed t test was applied to analyze the FTA and lateral joint space data. The nonparametric test (Wilcoxon's signed rank test) was applied to analyze the VAS and KSS data. A P value less than .05 was considered to be significant.
A total of 110 patients, including 34 males and 76 females (62 right knees and 48 left knees), were available for a mean follow-up of 49.1 months (range, 24–189 months) and were included in this study. These patients had an average age of 59.2 years (range, 47–69 years) at the time of surgery. Preoperatively, all patients reported limited range of knee motion, varus deformity, and severe knee pain, especially after increased weight bearing or athletic activities. Preoperative AP radiographs of the affected knees revealed narrow joint space in the medial compartments and sclerosis around the femorotibial joints (Figure 1). The patients had experienced OA for a range of 19 to 82 months. After partial fibular osteotomy was performed, 4 patients reported numbness in the ipsilateral lower leg, including 2 common peroneal nerve palsies and 2 superficial peroneal nerve injuries, all of which resolved within 3 to 10 months. The fibular osteotomy was performed at the level of the femoral neck in 3 of these patients and 6 to 10 cm below the fibular head in 1 patient. Sixteen patients reported weakness in the lower legs, and all returned to normal strength by 4 weeks. There were no superficial or deep infections. Four patients subsequently underwent total knee arthroplasty at a mean of 12.4 months (range, 7–17 months) after the osteotomy due to residual pain and unsatisfactory knee function.
At final follow-up, 110 patients with an average age of 63.5 years (range, 50–73 years) were evaluated clinically and radiographically. On postoperative AP radiographs, bone defects of the proximal fibula were observed in all patients. Radiographic measurements obtained preoperatively and at final follow-up are listed in Table 1. At final follow-up, mean FTA and lateral joint space were 179.4°±1.8° and 6.9±0.7 mm, respectively, which were significantly lower than the data measured preoperatively (P<.001). The lateral joint space was narrower and the medial joint space was wider than demonstrated on preoperative radiographs. Mean KSS at final follow-up was 92.3±31.7, which was significantly larger than the preoperative score (45.0±21.3; P<.001; Figure 4). Mean VAS score and interquartile range at final follow-up were 2.0 and 2.0, respectively, which were significantly lower than the preoperative data (7 and 1.0, respectively; P<.001; Table 2).
Preoperative and Final Follow-up Radiological Measurement Values
Pre- and postoperative American Knee Society (AKS) scores. The asterisk indicates a significant difference between the 2 groups.
Preoperative and Final Follow-up Visual Analog Scale Scores
High tibial osteotomy is a commonly used method to treat knee varus deformities due to OA. It aims to improve the mechanical axis passing from the center of the hip, through the knee joint, to the center of the tibiotalar joint in the coronal plane.15,16 Osteotomies performed proximal to the tibial tubercle may interfere with function of the patellar tendon.17-21 This patellofemoral disturbance is common in patients who have previously undergone proximal tibial osteotomies. In the authors' experience, a simple fibular osteotomy can relieve knee pain and correct varus deformity as effectively as high tibial osteotomy.
Bone mass decreases as part of the normal aging process.22 Varying degrees of settlement of bone mass exist in the load-bearing joints, such as the knees, hips, ankles, and spine. In the proximal tibia, the lateral support of the fibula to the lateral tibial plateau routinely leads to nonuniform settlement, which is more severe in the medial plateau than in the lateral plateau. The slope of the tibial plateau arising from nonuniform settlement results in a transverse shearing force, with the femoral condyle shifting medially during walking and sports.9 Furthermore, side-slip aggravates the nonuniform settlement of the tibial plateau, especially in the medial plateau. Accordingly, a cycle of increasing the load distribution in the medial compartment and nonuniform settlement occurs. There is also evidence that tibiofemoral articular stress distribution is related to the progression of knee OA.23 Based on these assumptions, the current authors hypothesized that the lateral support of the fibula to the tibial plateau is a key factor that leads to the nonuniform settlement of the bilateral plateau and the medial shift of the mechanical axis, resulting in degeneration and varus deformities of the knee joint.
This study confirms the safety and efficacy of partial fibular osteotomy in the treatment of medial compartment OA. Proximal osteotomy of the fibula weakens the lateral fibular support and leads to a correction of the varus deformity, which can subsequently shift the loading force from the medial compartment more laterally, leading to decreased pain and a satisfactory functional recovery. Mean KSS increased by 47.3 points in the final analysis. According to VAS scores, pain levels decreased significantly from severe to mild.
Although proximal fibular osteotomy is a simple procedure, care should be taken to avoid potential peroneal nerve injury. In this study, 4 (3.6%) patients reported numbness in the ipsilateral lower leg due to common peroneal nerve palsy (n=2) and superficial peroneal nerve injury (n=2). Based on this anatomical study and their own clinical experience, the authors recommend a posterolateral approach via the space between the peroneus longus and brevis muscle and soleus muscle to lessen the risk of iatrogenic nerve injury at a level of 6 cm before the fibular bed.
Limitations of this study include its lack of a control group for comparison and its nonprospective nature. Also, bias may be present because of the relatively small sample size.
Proximal fibular osteotomy may reduce knee pain significantly in the varus osteoarthritic knee and improve the radiographic appearance and functional recovery of the knee joint. It may delay or even negate the need for total knee arthroplasty. It is a safe, simple, and effective procedure that is an alternative to total knee arthroplasty for medial compartment OA of the knee joint. Care must be taken to avoid potential nerve injuries.
- Focht BC. Move to improve: how knee osteoarthritis patients can use exercise to enhance quality of life. ACSM's Health Fit J. 2012; 16:24–28.
- Felson DT, Naimark A, Anderson J, Kazis L, Castelli W, Meenan RF. The prevalence of knee osteoarthritis in the elderly: The Framingham Osteoarthritis Study. Arthritis Rheum. 1987; 30(8):914–918. doi:10.1002/art.1780300811 [CrossRef]
- Vincent KR, Conrad BP, Fregly BJ, Vincent HK. The pathophysiology of osteoarthritis: a mechanical perspective on the knee joint. PM&R. 2012; 4(5):S3–S9. doi:10.1016/j.pmrj.2012.01.020 [CrossRef]
- Shiozaki H, Koga Y, Omori G, Yamamoto G, Takahashi HE. Epidemiology of osteoarthritis of the knee in a rural Japanese population. Knee. 1999; 6(3):183–188. doi:10.1016/S0968-0160(99)00011-3 [CrossRef]
- Ahlbäck S. Osteoarthrosis of the knee: a radiographic investigation. Acta Radiol. 1968277(suppl):7–72.
- Wu LD, Hahne HJ, Hassenpflug T. A long-term follow-up study of high tibial osteotomy for medial compartment osteoarthrosis. Chin J Traumatol. 2004; 7:348–353.
- Sprenger TR, Doerzbacher JF. Tibial osteotomy for the treatment of varus gonarthrosis: survival and failure analysis to twenty-two years. J Bone Joint Surg Am. 2003; 85:469–474.
- Schnurr C, Jarrous M, Gudden I, Eysel P, Konig DP. Pre-operative arthritis severity as a predictor for total knee arthroplasty patients' satisfaction. Int Orthop. 2013; 37(7):1257–1261. doi:10.1007/s00264-013-1862-0 [CrossRef]
- Zhang Y, Li C, Li J, et al. The pathogenesis research of non-uniform settlement of the tibial plateau in knee degeneration and varus. J Hebei Med Univ. 2014; 35(2):218–219.
- Zheng Z, Sun Y, Zhang X, Chen W, Li S, Zhang Y. The pathogenesis and clinical imageology research of the knee osteoarthritis. J Hebei Med Univ. 2014; 35(5):599–600.
- Patond KR, Lokhande AV. Medial open wedge high tibial osteotomy in medial compartment osteoarthrosis of the knee. Natl Med J India. 1993; 6(3):104–108.
- Wang F, Chen B-C, Gao S. Influence of knee lateral thrust gait to femorotibial angle and lateral joint space in the knee varus patients. Chinese J Orthop. 2005; 25(9):517–519.
- Huskisson E. Measurement of pain. Lancet. 1974; 304:1127–1131. doi:10.1016/S0140-6736(74)90884-8 [CrossRef]
- Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res. 1989; 248(248):13–14.
- Hofmann S, Lobenhoffer P, Staubli A, Van Heerwaarden R. Osteotomies of the knee joint in patients with monocompartmental arthritis. Der Orthop. 2009; 38(8):755–769. doi:10.1007/s00132-009-1458-y [CrossRef]
- Weidenhielm L, Svensson OK, Brostromlk L. Surgical correction of leg alignment in unilateral knee osteoarthrosis reduces the load on the hip and knee joint bilaterally. Clin Biomech (Bristol, Avon). 1995; 10(4):217–221. doi:10.1016/0268-0033(95)91401-Y [CrossRef]
- Amendola A, Rorabeck C, Bourne R, Apyan P. Total knee arthroplasty following high tibial osteotomy for osteoarthritis. J Arthroplasty. 1989; 4:S11–S17. doi:10.1016/S0883-5403(89)80002-6 [CrossRef]
- Gill T, Schemitsch E, Brick GW, Thornhill TS. Revision total knee arthroplasty after failed unicompartmental knee arthroplasty or high tibial osteotomy. Clin Orthop Relat Res. 1995; 321:10–18.
- Hernigou P, Medevielle D, Debeyre J, Goutallier D. Proximal tibial osteotomy for osteoarthritis with varus deformity: a ten to thirteen-year follow-up study. J Bone Joint Surg Am. 1987; 69(3):332–354.
- Mont MA, Alexander N, Krackow KA, Hungerford DS. Total knee arthroplasty after failed high tibial osteotomy. Orthop Clin North Am. 1994; 25(3):515–525.
- Windsor R, Insall J, Vince K. Technical considerations of total knee arthroplasty after proximal tibial osteotomy. J Bone Joint Surg Am. 1988; 70(4):547–555.
- Newton-John H, Morgan D. Osteoporosis: disease or senescence?Lancet. 1968; 291(7536):232–233. doi:10.1016/S0140-6736(68)90853-2 [CrossRef]
- Segal NA, Anderson DD, Iyer KS, et al. Baseline articular contact stress levels predict incident symptomatic knee osteoarthritis development in the MOST cohort. J Orthop Res. 2009; 27(12):1562–1568. doi:10.1002/jor.20936 [CrossRef]
Preoperative and Final Follow-up Radiological Measurement Values
|Lateral joint space, mm||12.2±1.1||6.9±0.7||42.633||<.001|
Preoperative and Final Follow-up Visual Analog Scale Scores
|VAS Score||No. of Patients|